Means for and method of eliminating harmonic disturbances



Jan. 15 1924.

R. E. HELLMUND mus FOR AND us'rnon OF ELIMINATING mnuomc msrunmmcas Filed Dec. 14

INVENTOR PLdo/fZ/t/fln and.

WITNESSES:

ATTO RNEY Patented Jan. 15, 1 924. I

' UNITED STATES anneal-=1. mmnmn, or swrssvun, rmmsxLvanm, assmnon. 'ro wns'rnlenousn mncrmc a murac'runmo column, a coaromnou or rmmsYL- vam.

PATENT OFFICE.

FOB men 01' ELIIIN ATING HABKONIC DIBTUBBLNCE.

. "Application Med December 14, ms. Serial No. team.

To all whom it may concern:

Be it known that I, Runonr Hanmmm}, a citizen of the German Empire, and a resident of Swissvale, in the county of Alle-- 5 gheny and State of Pennsylvania, have invented a new and useful Improvement in Means for and Methods of Eliminatin Harmonic Disturbances, of which the fo owing is a specification.

My invention relates to means for absorb ing undesirable high-frequency currents which, while they may be necessa in the operation of certain electrical devices, are

productive of unsatisfactory results when allowed to flow in other portions ofelectrical circuits.

In many cases, it is necessary for satisfactory operation, that the'load ortrans-- the use of undesirable harmonic-current-ab-- sorption means in the circuits of alternatingcurrent rectifiers. It is well known that, while alternating-current rectifiers require, for, their satisfactory operation, currents of high frequency, it is desirable, if possible, to eliminate such high-frequency currents from the remainder of the electrical circuit.

I propose, therefore, to associate with rectifier circuits, means which will eliminate the high-frequency currents from the load circuit-s. fed by such rectifiers but, at the same'time, propose to so connect the absorption means that the rectifier itself will derive the necessary supply of such currents ffor satisfactory operation.

For a better understanding of 'my in vention, reference may be had to the accompanying drawings in which Figure 1 represents, diagrammatically, a load which causes currents having undesirable high frequencies, and the means for shown at 1 an eliminating such high-frequency currents; Fig. 2 illustrates, diagrammatically, a system in'which the undesirable currents are supplied to the line by the source or other in- I strumentalities exterior to the load itself; Figs. 3, 4 and 5 are diagrammatic views illustrating modifications of the systems shown in Figs. 1 and 2 and are especially related 'to' the application of such systems torectifier practices. 7

Referring. more particularly to Fig. 1, a load requiring high harmonic currents is is supplied with energy from any suitable source (not shown) by leads 2 and 3. Inserted in the leads 2 and 3 are inductive devices 4 and 5, for purposes hereinafter to be described.

Connected in parallel with the load 1 and between that load and the inductive devices 4 and 5, is a dynamo-electric machine 6 of the induction type having a primary member 7 and a squirrel-cage-wound secondary member 8. It will benoted that the primary member 7 is connected directly in parallel with the load 1 and that, therefdre, it con stitutes a shunt path for such currents as it mziy be desired to pass therethrough.

Fig. 2, the load 1 will operate satisfactorily with currents of the fundamental frequency only. -As shown, however, the line 2-3 carries currents of undesirable frequency in addition to the device-operating currents; It-isto be understood that such harmonic currents may come direct from the source, or it ma be due to some other load on the same circuit, such as may be caused by the condenser action of the line, that is to say, it may be due to' any instrumentality exterior to the load itself.

In this system, the eradicating means are connected between the source and the inductances 4 and 5 instead of between the load 1 and the inductances 4 and 5, as in Fig. 1.

In Fig. 3. a vapor rectifier.9.is shown as supplied with energy from a transformer 10 having a primary member 11 and a secondary member 12.

The rectifier 9 sn plies direct current to the load 1, which is ere shown as connected in a well known manner.

In this figure, the primary member 7 of the induction machine 6 is shown as connected in parallel relationship with the transformer secondary 12. The rotor 8 of the induction machine 6 is further provided with a direct-current winding 13 which is connected in parallel relationship to the inductive load and is, therefore, supplied with direct current in the manner indicated.

'An adjustable resistor 14 is connected in series relationship with the direct-current exciting winding'13, both being connected across the direct current terminals, and the effective resistance of the exciting circuit is adapted to be varied by, a segmental con tact member 15 which is, in turn, rotated by an auxiliary dynamo-electric machine 16 comprising an armature 17 anda field winding 18, the armature 17 serving to rotatively actuate the contact segment 15 through a shaft 19. The field winding 18 is split and is supplied with energy in such a manner that the armature 17 may be made. to rotav tively move in either direction, in accordance with the movement of an auxiliary motor relay 20 comprising an armature 21 and a field winding 22. A contact making mem-- ber 23 is attached to the armature 21, and by its movement closes the circuit between contact terminals 24 and 25 or between contact terminals 26 and 27.

The entire apparatus just described comprises a power-factor. relay which operates to so vary the resistance of the resistor 14 that the excitation of the winding 13 is adjusted automatically to best suit the conditions obtaining in the induction machine 6, as, for instance, so that its line frequency magnetizing current is zero or so that it furnishes wattless current to the transformer.

A series excited commutator machine 28, having an armature 29, series field winding 29* and a neutralizing field winding'29 all connected as shown, is employed to further improve the absorption of undesirable harmonic currents by promoting thefiow of such currents through the shunt circuit rather'than through the load.

For .purposes of adjustment, impedances 30, 30, and 30 are associated with the power-factor relay 20.

In Fig. 4:, another modification of the system above described is shown. The induc tance 5 is inserted in the primary side of the transformer, and across this inductance is connected the field winding 29 of the commutator machine 28. For purposes of convenience, I have not shown the powerfactor relay operatively connected in this figure, but it is to be understood that the relay described in connection with Fig. 3 may be used whenever circumstances require.

A capacity device 31 is connected in series with the independent field winding 29 and the inductance device 5 and, by proper adjustment, the inductive effect of the independent field and the resistance of the cir cuit, as Well as the phase and amplitude of the voltage induced in the armature of the machine 28, may be adjusted to compensate for the effect of the leakage reactance and resistance of the induction machine 6.

Another modification of my proposed system is illustrated in Fig. 5 wherein anode leads 32 and 33 are shown as having inductive windings 34 and 35', respectively,1n circuit therewith, and inductively interlinked with a further inductive winding 36 which is connected in series with the independent field windin 29 of the rotor 28. In this figure, as in Fig. 4, a capacity device 31 is also shown in the circuit.

Having described a number of systems constructed in accordance with my invention, the operation thereof is as follows As above-mentioned, a number of loads, Such as rectifiers, require high harmonic currents for their satisfactory operation and it is necessary, therefore, to provide such currents. At the same time, however, provision should be made to eliminate them higher harmonic currents which it is desiredto elgminate, andthey will, therefore, be shunte out of the main supply circuit. The inductive devices 4: and 5, being placed between the line and the eradicating means.

assist in forcing the undesirable currents through the latter.

In Fig. 2 it is assumed that the load is supplied with energy from a line in which currents of differing frequencies are flowing, but that, for satisfactory operation, itmust be supplied with currents of the fundamental frequency only. The eradicating means 6 is placed, therefore, between the source and the inductive devices 4: and 5, these latter serving to promote the flow of the undesirable currents through the winding 7.

ieferring now to Fig. 3. it will be noted that the rectifier is shown as supplied with alternating current from the secondary of the transformer and is, in turn, supplying direct current to a load 1, in the well known manner. It, therefore, becomes necessary to eliminate the ripple currents from the 1 load circuit 1, but, at the same time, to allow them to fiow freely in the supply circuit of the rectifier.

loo

assists in causing the currents to flow in thements shown in Figs; 4 and 5.

In this connection, 'use is made of the machine 6 provided with the direct-currentexcited winding 13, and connected across the secondary of the transformer. This system has the advantage that the leakage reactance of the transformer assists in keeping the higher harmonics out of the line w ich may render the use of inductances 4 and 5 unnecessary. Even if the inductance 4 is used, it may be made small.

Moreover, the use of a synchronous machine has the advantage that the power factor in' the primary winding may be adjusted and that, thereby, it is possible to shift whatever small irregularity in the wave.

shape which is not eliminated by the machine 6 to a oint on the voltage curve where it is least 0 jectionable in its effect.

The auxiliary commutator machine 28 is run in such manner and excited in such direction that the voltage generated therein desired circuit. A machine employed in this manner is known inthe art as a negative im dance.

he auxiliary apparatus, herein described as constituting the power-factor relay, is automatically operated by the current in the primary circuit of the transformer to adjust the power factor in the desired manner and especially so that line frequency currents of the desired amplitude shall flow in the shunt circuit.

The system described in connection with Fig. 4 operates in a similar manner to those above described with the exception that the current flowing in the independent field winding 29 of the auxiliary machine 28 is varied by properly adjusting the capacity device 31. This latter method of adjusting the current in the independent field winding is productive of very satisfactory compensation of the leakage reactance and resistance of the main induction machine 6.

In Fig. 5 the current supplied tothe independent field winding is varied in accordance with the load current of the rectifier, by reason of the inductive interlinkage of the three coils 34, 35 and 36. The auxiliary inductive winding 36 is so arranged that .it carries the sum of the two currents flowing in the anode leads.

With the addition of the booster machine 28, the machine 6 might be replaced by a highly saturated inductance, capacity, or even a high resistance, with the arrange- In some cases it is possible to use a commutator machine only, assuming, however, that its excitation is properly adjusted. Before the rectifier is operative, the booster machine 28 may be used for startingservice. In all cases, the induction motor is especially designed for low inductance and resis nce.

While I have shown and describe several modifications of a system in which undesirable high-harmonic-absorption means are placed, it is apparent that many modifications in the manner of connection, specific apparatus used, etc. may occur to those skilled in the art, and I desire, therefore, that the widest possible interpretation be placed on the appended claims.

I claim as my invention:

1. An electrical system comprising alternatingcurrent mains having translating devices connected thereto having negligibly small harmonic currents, second alternatingcurrent mains having a translating device demanding abnormally large harmonic currents such as would harm the devices on said first-mentioned mains, connections between said first and second-mentioned mains and including series inductance, and a shuntconnected induction machine having a short-circuited secondary winding and having its primary winding connected to said second-mentioned mains.

2. In combination with an alternatingcurrent circuit and a rectifier for interconnecting said circuit with a direct-current circuit, dynamo-electric means connected in parallel with said rectifier, and constituting a path of high impedance for currents having the frequency of said alternatingcurrent circuit and low impedance for the undesirable-frequency currents occasioned by the operation of said rectifier, and a series inductance device between said alternatin -current circuit and said rectifier.

3. n combination with an alternatingcurrent circuit and a rectifier connected thereto, a squirrel-cage induction machine having its primary connected in parallel with said rectifier, and a series inductance device included'in the connections between said rectifier and said alternating-current circuit.

4. In combination with an alternatingcurrent circuit and a rectifier connected thereto, an induction machine having a primary yvinding connected in parallel with said rectifier. and having a low-impedance polyaxially short-circuite-d secondary winding and means whereby power factor con trol may be obtained through said induc tion machine.

5. In combination with an alternatingcurrent circuit, a rectifier and a transformer having primary and secondary members connected respectively to said circuit and said rectifier, dynamo-electric means energized from said transformer connected in parallel with said rectifier and constituting a path of relatively high impedance for currents having the frequency of said alternating-current circuit, and relatively low impedance for the undesirable-frequency currents occasioned by the operation of said rectifier.

6. In combination with an' alternatingcurrent circuit, a rectifier and a transformer having primary and secondary members connected respectively to said circuit and said rectifier, a dynamo-electric machine.

having primary, secondar and unidirectional-current windings, sai primary winding being connected to said transformer in parallel with said rectifier, said secondary winding being polyaxially short-circuited,

power factor control means COIHPI'ISHIgfor adjusting the phase of the higher har-- monies relative to the phase of the primary fundamental wave of the transformer circuit.

8. In combination with an alternatingcurrent circuit, a rectifier connected thereto, an induction machine having a primary connected in parallel with said rectifier, and means for adjusting the phase of the higher harmonics occasioned by the operation of said rectifier relative tothe phase of the fundamental wave of the alternating-current circuit.

9. In combination with an alternatingcurrent rectifier and a transformer supply ing power thereto, dynamo-electric means for adjusting the phase of the higher-harmonic currents relative to the phase of the primary fundamental wave of the transformer current.

10; In combination with an alternatingcurrent rectifier, means for absorbing higher-harmonic currents caused by the operation of said rectifier, and a commutatortype dynamoelectric machine having an armature and a field winding, said'field winding being so energized and said armature being so connected, that the voltage developed in said armature shall promote the flow of said higher harmonics in said absorbing means. I

.11.-In combination with an alternatingcurrent rectifier, means for absorbing higher-harmonic currents caused by the operation of. said rectifier, and a commutatortype dynamo-electric machine having an armature and 'a field winding, and a condenser in said field winding circuit serving to cause the voltage developed in said armature to promote the flow of said higher harmonics in said absorbing means.

12. In combination with an alternatingcurrent rectifier supplied with energy from the secondary of a transformer, and having cathode and anode leads, inductive windings in each of said anode leads, means for absorbing higher-harmonic currents caused by the operation of said rectifier, and a commutator-type dynamo-electric machine having an armature and a field windin an inductive winding in said field-winding circuit, said winding being inductively interlinked with said anode-lead windings, whereby said field winding is energized.

, 13. The combination with a circuit carrying currents of different frequencies, of a second circuit carrying currents of only one of said frequencies, dynamo-electric means connected in parallel across both of said circuits, said dynamo-electric. means oiferin a relatively high impedance to currents o the frequency of said second circuit and a relatively low impedance to currents-of the other frequencies, the connections between said dynamo-electric means and said first.

' mentioned circuit being of relatively low impedance, and the connections between said dynamo-electric means and said second circuit offering a relatively low impedance to currents of the frequency'of said second circuit and a relatively high impedance to currents of the other frequencies.

' 14. The combination with a circuit carrying currents of a plurality of frequencies. of an electrical device connected-thereto and adapted to carry currents of only one of said frequencies, selective-frequency means connected to said circuit for substantially eliminating currents of all other frequencies I from said device, and means responslve to the currents of whatever frequencies flowing in said selective-frequency circuit .to

minimize the impedance of said last-mentioned circuit to said last-mentioned currents. f

15.. The combination with a circuit carrying currents of a luralit'y of frequencies, of an electrical devloe' connected thereto and adapted to carry currents of only one of said frequencies, selective-frequency. means connected in shunt with said device and offering'a high-impedance to currents of said frequency and a low impedance to currents of all other frequencies, and. a booster in the.

shunt circuit for generating an assisting electromotive force responsive to the currents flowing therein.

16. The combination as'specified in claim 15, including as the selective frequency means an induction machine adapted to offer asynchronous impedance to currents of the frequency obtaining in said device.

17. The combination as specified in claim 15, including as the booster a series, commutator-type alternating current machine.

18. In the combination of a circuit carrying currents of a plurality of frequencies, an electrical device connected thereto and 1n auxiiiary adapted to carry currents of only one of said frequencies, selective-frequency means connected. in shunt with said device and offering a high impedance to currents of said frequency and a low impedance to currents of all other frequencies, and a booster connected in series circuit relationship with said selective-frequency means and adapted to be responsive to currents of all frequencies flowing in said means, the method of substantiall precluding the flow of all but the desire frequency cur rents in said device, which consists in operating said booster under such conditions of speed and excitation that the low impedance of said shunt circuit to currents of said other frequencies is substantially reduced.

19 In combination with an alternating e12 rib-rectifier, selective-impedance means connected in shunt therewith for absorbing iigiier-iiarmonic currents caused by the eration of said rectifier, and means arranged to introduce into the absorbing circuit an electromotive force assisting the flow of current therein.

20. In combination with an alternatingcurrent rectifier, selective-impedance means for absorbing higher-harmonic currents caused by the o eration of said rectifier, and ynamo-electric machine arranged to introduce into the absorbing cirsuit an eiectromotive force assisting the current-flow in said harmonic-absorbing means.

21. The combination with an alternatin current circuit including a device whic would be harmed by abnormally large harmonic currents, of a double-wave rectifier device carrying such harmonic currents, seiective impedance means for offering a relativeiy low impedance to one or more of said harmonic currents, said means being connected. in shunt relation, to said rectifier demise, and inductance means serially connected between said circuit and said rectifi device.

22. The combination, with an alternatin current circuit including a device whic would be harmed by abnormally large armonic currents, of a rectified-current decarrying such harmonic currents, selecn impedance means associated with said it for providing a shunt path of rela Lively iow impedance to one or more of said harmonic currents, and a series booster device inserted in series with said selectiveimpedance means for augmenting. the flow of currents of whatever frequency flowing therein.

23. The combination with an alternatingcurrent supply-line, of a transformer for derivin two secondary electomotive forces there rom, means for providing a pair of oppositely disposed asymmetrically conducting paths respectively associated with said secondary electromotive forces, a direct-cur rent circuit operatively associated with said paths, and selectiredmpedance means associated with the secondary electromotive forces of said transformer for providing a shunt path of relatively low impedance to one or more of said harmonic currents, whereby said transformer operates, in effect, as an inductance device serially connected to said supply-line.

24. The combination with an alternatingcurrent supply-lino, of. a transformer for deriving two secondary electromotive forces therefrom, means for providing a pair of oppositely disposed asymmetrically conducting paths respectively associated. with. said secondary elcctromotive forces, a direct-cur rent circuit operatively associated with said paths, and a light running dynamo-electric machine having primary windings associated with said secondary electromotive forces and having a closely coupled, iowdnu pedance secondary winding, whereby said transformer operates, in effect, as an inductance device serially connected to said. supply line.

25. The combination with an alternatingcurrent supply-line, of a transformer for do riving two secondary electromotive forces therefrom, means for providing a pair of oppositely disposed asymmetrically conducting paths respective y associated with said secondary electromotive forces, a direct'cun rent circuit operatively associated with said paths, a light running dynamo-electric machine having primary windings associated with said secondary electromotive forces and havin a closely coupled, low-impedance secon ary winding, and a negative impedance device inserted in series with said dynamo-electric machine for augmenting the flow of currents of whatever frequency iiowing therein.

In testimony whereof, I have hereunto subscribed my name this 4th day of December, 1918.

RUDOL-F E. HELLMUND,

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